Roof Truss Step Bottom Chord

Flat the most economical flat truss for a roof is provided when the depth of the truss in inches is approximately equal to 7 of the span in inches.

Roof truss step bottom chord.

Create a bottom chord while you have established the angle of the trusses with your rafter pieces and cut them in the necessary lengths they still need more support to finish the structure. A domestic roof engineered truss has had the bottom cord cut to install an attic access hatch door. To keep the plywood from cupping under the load 2x4 squash blocks were to be inserted between the top and bottom chords. The adjoining trusses appear slightly out of plain.

This is where you will make a bottom chord. The bottom chord establishes the lower edge of a truss. The span in short is the length of the bottom of the truss. The bottom chord is also called a scissors truss.

It will attach to the bottom of each end of the rafters with a straight length of wood. For example if a truss has a span of 26 then the bottom chord can be built with two boards 16 and 10 which allows for no scrap and waste and is the most efficient for price savings. One truss cut only at the third point. The node gang nail at the cut point looks in distress and has partially pulled out.

To reinforce the ends of the trusses 3 4 inch plywood gussets were to be attached to both sides of each truss with 10d nails 3 inches on center on all chords. Some spans have a lower rate per foot than others. Most economical when the difference in slope between the top and bottom chords is at least 3 12 or the bottom chord pitch is no more than half the top chord pitch.